Featured Research

from universities, journals, and other organizations

Key To Life Before Its Origin On Earth May Have Been Discovered

Date:
February 29, 2008
Source:
Arizona State University
Summary:
An important discovery has been made with respect to the mystery of "handedness" in biomolecules. Researchers have found that some of the possible abiotic precursors to the origin of life on Earth have been shown to carry "handedness" in a larger number than previously thought. Scientists have long known that most compounds in living things exist in mirror-image forms. The two forms are like hands; one is a mirror reflection of the other. They are different, cannot be superimposed, yet identical in their parts. When scientists synthesize these molecules in the laboratory, half of a sample turns out to be "left-handed" and the other half "right-handed." But amino acids, which are the building blocks of terrestrial proteins, are all "left-handed," while the sugars of DNA and RNA are "right-handed." The mystery as to why this is the case, "parallels in many of its queries those that surround the origin of life," one of the researchers said.

Fragment of the Murchison meteorite (at right) and isolated individual particles (shown in the test tube).
Credit: DOE/Argonne National Laboratory

An important discovery has been made with respect to the mystery of "handedness" in biomolecules. Researchers led by Sandra Pizzarello, a research professor at Arizona State University, found that some of the possible abiotic precursors to the origin of life on Earth have been shown to carry "handedness" in a larger number than previously thought.

Pizzarello, in ASU's Department of Chemistry and Biochemistry, worked with Yongsong Huang and Marcelo Alexandre, of Brown University, in studying the organic materials of a special group of meteorites that contain among a variety of compounds, amino acids that have identical counterparts in terrestrial biomolecules. These meteorites are fragments of asteroids that are about the same age as the solar system (roughly 4.5 billion years.)

Scientists have long known that most compounds in living things exist in mirror-image forms. The two forms are like hands; one is a mirror reflection of the other. They are different, cannot be superimposed, yet identical in their parts.

When scientists synthesize these molecules in the laboratory, half of a sample turns out to be "left-handed" and the other half "right-handed." But amino acids, which are the building blocks of terrestrial proteins, are all "left-handed," while the sugars of DNA and RNA are "right-handed." The mystery as to why this is the case, "parallels in many of its queries those that surround the origin of life," said Pizzarello.

Years ago Pizzarello and ASU professor emeritus John Cronin analyzed amino acids from the Murchison meteorite (which landed in Australia in 1969) that were unknown on Earth, hence solving the problem of any contamination. They discovered a preponderance of "left-handed" amino acids over their "right-handed" form.

"The findings of Cronin and Pizzarello are probably the first demonstration that there may be natural processes in the cosmos that generate a preferred amino acid handedness," Jeffrey Bada of the Scripps Institution of Oceanography, La Jolla, Calif., said at the time.

The new PNAS work* was made possible by the finding in Antarctica of an exceptionally pristine meteorite. Antarctic ices are good "curators" of meteorites. After a meteorite falls -- and meteorites have been falling throughout the history of Earth -- it is quickly covered by snow and buried in the ice. Because these ices are in constant motion, when they come to a mountain, they will flow over the hill and bring meteorites to the surface.

"Thanks to the pristine nature of this meteorite, we were able to demonstrate that other extraterrestrial amino acids carry the left-handed excesses in meteorites and, above all, that these excesses appear to signify that their precursor molecules, the aldehydes, also carried such excesses," Pizzarello said. "In other words, a molecular trait that defines life seems to have broader distribution as well as a long cosmic lineage.""

This study may provide an important clue to the origin of molecular asymmetry," added Brown associate professor and co-author Huang.

*The work is being published in the Early Edition of the Proceedings of the National Academy of Sciences. The paper is titled, "Molecular asymmetry in extraterrestrial chemistry: Insights from a pristine meteorite," and is co-authored by Pizzarello, Huang and Alexandre.


Story Source:

The above story is based on materials provided by Arizona State University. Note: Materials may be edited for content and length.


Cite This Page:

Arizona State University. "Key To Life Before Its Origin On Earth May Have Been Discovered." ScienceDaily. ScienceDaily, 29 February 2008. <www.sciencedaily.com/releases/2008/02/080228174823.htm>.
Arizona State University. (2008, February 29). Key To Life Before Its Origin On Earth May Have Been Discovered. ScienceDaily. Retrieved September 21, 2014 from www.sciencedaily.com/releases/2008/02/080228174823.htm
Arizona State University. "Key To Life Before Its Origin On Earth May Have Been Discovered." ScienceDaily. www.sciencedaily.com/releases/2008/02/080228174823.htm (accessed September 21, 2014).

Share This



More Space & Time News

Sunday, September 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

SpaceX Cargo Ship Blasts Off Toward Space Station

SpaceX Cargo Ship Blasts Off Toward Space Station

AFP (Sep. 21, 2014) SpaceX's unmanned Dragon cargo ship blasts off toward the International Space Station, carrying a load of supplies and science experiments for the astronauts living there. Duration: 00:35 Video provided by AFP
Powered by NewsLook.com
MIT BioSuit A New Take On Traditional Spacesuits

MIT BioSuit A New Take On Traditional Spacesuits

Newsy (Sep. 19, 2014) The MIT BioSuit could be an alternative to big, bulky traditional spacesuits, but the concept needs some work. Video provided by Newsy
Powered by NewsLook.com
Boeing, SpaceX to Send Astronauts to Space Station

Boeing, SpaceX to Send Astronauts to Space Station

AFP (Sep. 17, 2014) NASA selected Boeing and SpaceX on Tuesday to build America's next spacecraft to carry astronauts to the International Space Station (ISS) by 2017, opening the way to a new chapter in human spaceflight. Duration: 01:13 Video provided by AFP
Powered by NewsLook.com
East Coast Treated To Rare Meteor Sighting

East Coast Treated To Rare Meteor Sighting

Newsy (Sep. 16, 2014) Numerous residents along the East Coast reported seeing a bright meteor flash through the sky Sunday night. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins